Greeley Terry Ranch Pipeline

Challenges

The City of Greeley’s (Greeley) population is expected to grow to over 260,000 residents by 2065.  Greeley is implementing a generational aquifer storage and recovery project to meet long-term water demands.  The project will allow Greeley to access up to 1.2 million acre-feet of water from deep underground aquifers in northwest Weld County.

Water from the aquifer will be conveyed to Greeley’s water treatment plants through a 36-inch-diameter, 33-mile-long pipeline. The pipeline crosses multiple roadways, irrigation canals, and streams, requiring seven tunnel installations, each with unique design and construction considerations.

Solution

RJH was retained as part of the construction management team to provide specialty engineering services for tunnel and shaft construction. The pipeline was designed and installed in two segments under a Construction Management at Risk contract. Segment 1 was advanced to a 100-percent level and Segment 2 was advanced to a 60-percent level for construction. RJH reviewed plans and specifications for the tunnels and shafts for both segments. The tunnels ranged from approximately 100 to 200 feet long, and tunneling methods included guided pipe ramming, tunnel boring machine, guided auger bore, and McLaughlin on-target steering.

During the pre-construction phase, RJH reviewed the quality assurance plan, risk register, and construction schedule for the tunnels and shafts. RJH provided full-time field engineering services to observe and document the construction of the shafts and tunnels and identify compliance with contract documents.